What feels like forever ago, I described a method Split Screen Screenshots that allow you to put a copy of the same web page into two frames, so that you can grab a screenshot that includes the page header in the top frame, for example, as well as something from waaaaaay down the page in the lower frame.
I didn’t realise that the recipe I described required help from an external service until I tried to reuse the method to grab the following screenshot…
Anyway, cribbing from this Chrome Dual View standalone bookmark, here’s an updates version of my split screen bookmarklet:
javascript:url=location.href;f='<frameset rows=\'30%,*\'>\n<frame src=\''+url+'\'/><frame src=\''+url+'\'/></frameset>';with(document){write(f);void(close())}
To make use of it, drag the following link onto you bookmark toolbar, or save the link as a bookmark: Hmm… seems the craptastic WordPress.com doesn’t let me post bookmarklet links? So you’ll have to: bookmark this page, edit the bookmark, paste the above code snippet into the URL. Then when you want to split the view of a webpage, just click the bookmarklet.
OUseful.Info, the blog... 
Mr. Hirst: snippet not working for me. Return for this page reads “https://blog.ouseful.info/2015/01/15/split-view-web-page-bookmarklet/.” Same for any page: returns link to page to be split instead of splitting. I copy/pasted your code. Help?
WordPress possibly messing up the code. I popped a clean version of it on pastebin: http://pastebin.com/uU1WL7RD
Yes. That worked. Thank you!